Acetoxsilicon adhesion promoter and primer composition

ABSTRACT

Reaction products obtained by mixing under anhydrous conditions   WHERE K IS 0 TO 20 AND A is methyl or vinyl and   WHERE M IS 0 TO 5 AND Y IS 1 OR 2 ARE ADHESION PROMOTERS WHICH ARE USEFUL IN PRIMER COMPOSITIONS. The primer compositions are organic solvent solutions with 50 to 99.9 weight percent organic solvent, with the balance being made up of 5 to 100 weight percent of the adhesion promoter, 0 to 50 weight percent of alkylsilicate and 0 to 50 weight percent of an organotitanate. An example of a primer composition would be a solution of 76.9 weight percent inhibited 1,1,1-trichloroethane with 23.1 weight percent of equal weight amounts of an adhesion promoter where A is vinyl, k is 3 and m has an average value of about 0.7, ethylpolysilicate and bis(acetylacetonyl)diisopropyltitanate. The primer compositions are useful in adhering room temperature vulcanizable silicone elastomers to substrates such as aluminum.

United States Patent [1 1 Lee et al.

[ Oct. 21, 1975 ACETOXYSILICON ADHESION PROMOTER AND PRIMER COMPOSITION [73] Assignee: Dow Corning Corporation, Midland,

Mich.

221 Filed: Oct. 12, 1973 21 Appl. No.: 406,065

[44] Published under the Trial Voluntary Protest Program on January 28, 1975 as document no.

[52] US. Cl. ..260/32.8 SB; 260/33.6 SB; 260/33.8 SB

[51] Int. CL? C08K 5/07 [58] Field of Search 260/32.8, 33.6, 33.8

[56] References Cited UNITED STATES PATENTS 3,377,309 4/1968 Harper 260/32.8 SB 3,677,998 7/1972 Young 260/33.6 SB

Primary Examiner-Lewis T. Jacobs Attorney, Agent, or FirmRoger l-l. Borrousch 5 7 ABSTRACT Reaction products obtained by mixing under anhydrous conditions where k is 0 to 20 and A is methyl or vinyl and {OCCHQ I in where m is O to 5 and y is 1 or 2 are adhesion promoters which are useful in primer compositions. The primer compositions are organic solvent solutions with 50 to 99.9 weight percent organic solvent, with the balance being made up of 5 to 100 weight percent of the adhesion promoter, 0 to 50 weight percent of alkylsilicate and 0 to 50 weight percent of an organotitanate. An example of a primer composition would be a solution of 76.9 weight percent inhibited l,l,l-trichloroethane with 23.1 weight percent of equal weight amounts of an adhesion promoter where A is vinyl, k is 3 and m has an average value of about 0.7, ethylpolysilicate and bis(acetylacetonyl)diisopropyltitanate. The primer compositions are useful in adhering room temperature vulcanizable silicone elastomers to substrates such as aluminum.

19 Claims, No Drawings 3 ,914 1 ACETOXSILICON ADHESION PROMOTER AND PRIMER COMPOSITION BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to an adhesion promoter and primer compositions prepared therefrom.

2. Description of prior art Adhering silicone elastomers to various substrates is a continuing problem. There is an ever present need for better adhesion. With the changing substrates and silicone elastomers, the search for new methods of adhering the silicone rubber to substrates and for new materials to provide adhesion continues. One particlar area wherein adhesion is required, is the application where room temperature vulcanizable silicone elastomer is to be adhered to substrates, such as metals. Many of the prior art methods of adhering silicone rubber to substrates are not suitable for todays materials, provide an insufficient bond strength or are too expensive because of the complex method or materials.

Keil in U.S. Pat. No. 2,751,314 teaches that silicone rubber can be adhered to the surface of a solid by de positing a continuous coating having 50 to 100 percent by weight of an organotitanate and O to 50 weight percent alkylpolysilicate, depositing over this coating another coating having 1 to 10 percent by weight alkylpolysilicate and 90 to 99.9 ofa toluene soluble organopolysiloxane, thereafter applying a silicone rubber such as a room temperature vulcanizable silicone rubber. While this method described by Keil does bond silicone rubber to a substrate, it requires two coatings to provide an adequate bond and it also shows that a silicone rubber layer containing alkylpolysilicate must be deposited over the titanate primer layer to achieve adequate bonding.

Harper in U.S. Pat. No. 2,979,420 teaches that a room temperature vulcanizing silicone rubber can be bonded to a surface by applying certain monoorganotriacyloxysilanes to the surface as a primer. Although this method is simple, the bonding achieved is insufficient in strength for many applications.

Chadha in U.S. Pat. No. 3,498,824 teaches that an alkoxyayloxysilane can be used as a primer to adhere room temperature vulcanizing silicone rubber to metal substrates. Although the bond strength is improved with this primer compared to no primer, the bond strength is insufficient under many circumstances.

Young in U.S. Pat. No. 3,671,483 teaches that certain compositions are useful as primers for adhering silicone rubber to epoxy resin and polyurethane substrates. The compositions described contain alkylsilicates, organotitanates, solvent and a compound of the formula modified organosiloxane having in addition to the above siloxane units, (CH COO) SiCH CH (CH )SiO units and Units. These primer compositions are suitable for adhering silicone rubber to substrates in certain applications but have insufficient bond strength for many applications and additionally have a potential to form hydrogen gas because of the presence of silicon bonded hydrogen atoms.

There are many other methods used to adhere silicone rubber to substrates, most do not achieve bond strengths of the magnitude obtained by the compositions of the present invention and those which approach such strengths have other limitations, such as decreasing strengths on standing, loss of adhesion by heat aging, by solvent action and the like.

SUMMARY OF THE INVENTlON An object of this invention is to provide a composition suitable for providing strong adhesive bonds between room temperature vulcanizable silicone elastomers and substrates.

This invention relates to an adhesion promoter prepared by mixing vinylsiloxane and an acetoxysilicon compound, to compositions consisting essentially of an adhesion promoter, an alkylsilicate and an organotitanate in an organic solvent solution. These compositions are useful as primers when applied to substrates such as metals, and thereafter curing silicone elastomers on this primed surface. Silicone elastomers cured by the reaction of alkenylsiloxane, silicon-bonded hydrogen atoms and a platinum catalyst adhere particularly well whereas other primers do not provide as good adhesion for this type of silicone elastomer.

DESCRIPTION OF THE lNVENTlON This invention relates to a composition under anhydrous conditions consisting essentially of an organic solvent solution of (a) a reaction product obtained by mixing under essentially anhydrous conditions (1) an organosiloxane of the formula CH CH ASi (OSi) OH I I k CH CH in which A is a monovalent radical selected from the group consisting of vinyl and methyl radicals and k has an average value of from 0 to 20 inclusive where the organosiloxane species having values of k above 20, if present, are in no more than minor amounts and (2) an acetoxysilicon compound of the formula in which m has an average value of from 0 to 5 inclusive and y is 1 or 2, (1) and (2) being mixed in proportions to provide a ratio of hydroxyl in l to acetoxy in (2) of from 1/14 to A, (b) an alkyl silicate selected from the group consisting of ethylorthosilicate, propylorthosilicate, ethylpolysilicate and propylpolysilicate, and (c) an organotitanate of the formula Ti(OR) wherein each -OR is a monovalent radical selected from the group consisting of alkoxy radicals having from 1 to 5 carbon atoms and acetylacetonoxy, (a) provides 5 to 100 weight percent, (b) provides to 50 weight percent and (c) provides 0 to 50 weight percent, where (a), (b) and (0) equals, 100 weight percent, said organic solvent solution being from 50 to 99.9 weight percent of'an organic solvent selected from the group consisting of ketones, halogenated hydrocarbons and hydrocarbons all having boiling points no greater than 150C.

The compositions are prepared and stored under essentially anhydrous conditions, because the acetoxy functionality on the silicon compounds is reactive with moisture.

The reaction product (a) is prepared by mixing an organosiloxane and an acetoxysilicon compound under anhydrous conditions. The organosiloxane (1) has formula CH3 CH3 ASi(OSi) OH I I k CH CH CH CH 1 r I I I CH =CHSiOH and CH =CHSi(OSi) OH.

r r I CH5 CH CH A number of methods are known in the art for the preparation of the organosiloxanes of (1). One method is described by Brown and Hyde in U.S. Pat. No. 3,162,662 wherein a triorganochlorosilane can be reacted with hexamethylcyclotrisiloxane in the presence of acetonitrile and N,N-dimethylacetamide. For this invention, the triorganochlorosilane would be trime thylchlorosilane or dimethylvinylchlorosilane. This method provides a monochlorine endblocked diorganopolysiloxane which can then be hydrolyzed under mild hydrolysis conditions to silanol. The hydrolysis of trimethylchlorosilane and dimethylvinylchlorosilane form the corresponding silanols under mild hydrolysis conditions. By mild hydrolysis conditions, it is to be understood that condensation of the newly formed silanols is minimized where this can readily be accomplished by the use of buffered solutions to keep the pH about 7. The organosiloxanes having various k values can be prepared by allowing the reaction between the chlorosilane and cyclotrisiloxane to continue over various periods of time and then separating the resulting mixture by such methods as the spinning band technique. The separations can be used to obtain single species or mixtures having a desirable average k value. U.S. Pat. No. 3,162,662 is hereby incorporated by reference to show the preparation of the chlorine endblocked organosiloxanes which can be hydrolyzed to the organosiloxanes (1).

The acetoxysilicon compounds (2) have a formula O a)2-y H3)2-y 0 II I II (CHgCO) Si Oi OCCH OCCH I a m where m is O to 5 and y is 1 or 2. Specific examples of the acetoxysilicon compound (2) include methyltriacetoxysilane, tetraacetoxysilane and partial hydrolyzates thereof to provide the values of m from above 0 to 5. These partial hydrolyzates of the silanes such as methyltriacetoxysilane can be readily obtained by slowly adding the necessary amount of water to the methyltriacetoxysilane to obtain the desired average value of m. Theoretically it requires one-half mole of water per mole of acetoxy to hydrolyze and condense. The partial hydrolyzates having an average value for m of 0.5 to l are the preferred acetoxysilicon compounds wherein optimum adhesion results are obtained in priming compositions prepared therefrom.

The organosiloxane l and the acetoxysilicon compound can be mixed in proportions to provide a ratio of hydroxyl in (1) to acetoxy in (2) of from 1/14 to 15;, preferably from A; to 9%. As long as (l) and (2) are mixed under essentially anhydrous conditions, the product obtained is useful as an adhesion promoter, particularly in the primer compositions. This reaction product can be prepared and used in making the primer compositions or the organosiloxane l and the acetoxysilicon compound (2) can be added separately in making the primer composition.

The alkylsilicates of (b) are known in the art and include ethylorthosilicate, propylorthosilicate, ethylpolysilicate and propylpolysilicate. These materials can be purchased commercially. The preferred alkylsilicate is ethylpolysilicate.

The organotitanates of (c) have a formula Ti oR where each OR is an alkoxy radical of l to 5 carbon atoms such as methoxy, ethoxy, propoxy, isopropoxy, butoxy and amyloxy or acetylacetonoxy. Specific examples include, tetrabutyltitanate, tetraisopropyltitanate, bis(acetylacetonyl)diisopropyltitanate, bis- (acetylacetonyl)-diethyltitanate, bis(acetylacetonyl)- dimethyltitanate and tetramethyltitanate. The preferred organotitanate (c) is bis(acetylacetonyl)diiso propyltitanate.

The organic solvents are those which have boiling points no greater than C. and include ketones such as acetone, methylethylketone, methylisobutylketone,

obtained when the organotitanate is added last. Preferably, the adhesion promoter is added to the organic solvent, followed by the alkylsilicate and the organotitanate. In those compositions wherein the reaction product is not used and the organosiloxane (l) and acetoxysilicon compound (2) are added separately, the order of addition of (l) and (2) is not critical. I

The primer compositions can be prepared with 50 to 99.9 weight percent organic solvent. The best results are obtained with the more dilutesol utions such as from 75 to 99 weight percentorganic solvent. The remainder of the primer composition, 0.1 to 50 weight percent is adhesion promoter (a) or a combination of (1) and (2) and, if present, alkylsilicate (b) and organotitanate (c), where these ingredients make up 100 weight percent of the remainder.

Primer compositions can be prepared where the ingredientsother than. organic solvent are 5 to 100 weight percent adhesion promoter (a) or a combination of l and (2) when added separately, from to 50 weight percent alkylsilicate (b) and 0 to 50 weight percent organotitanate (c). Preferably (b) is present in at least 10 weight percent and (c) is present in at least 4 weight percent. The primer compositions which were found to provide the best adhesion of silicone elastomer to substrates are those which contain at least 10 weight percent (a), at least 20 weight percent (b) and at least 10 weight percent (0).

The primer compositions are applied to the substrate surfaces to which silicone elastomer is to be applied, in extremely thin layers. The primer composition can be applied by wiping, brushing, spraying and the like. The best results are obtained when, as much of the primer composition is wiped off, after being applied, as possible. After the substrate has been primed, the solvent evaporates before the silicone elastomer is placed over the primed surface. The silicone elastomer can then be either cured at room temperature orheat vulcanized. The resulting cured silicone rubber is securely bonded to the substrate. This primer composition is particularly suited for metal substrates, such as aluminum, stainless steel, titanium and the like. The silicone elastomers can be either pourable compositions or flowable compositions which can be extruded from a tube or stiff compositions which are prepared from gum bases.

The primer compositions of this invention are partic ularly useful for silicone elastomers which cure by the addition reaction of silicon-bonded alkenyl radicals with silicon-bonded hydrogen atoms in the presence of a platinum catalyst. These silicone elastomers are known to the art and are available commercially in many forms.

The following examples are presented for illustrative purposes only and should not be construed as limiting the present invention which is properly delineated in the claims.

EXAMPLE 1 I To a 5 liter flask, 436 grams of acetonitrile and 43.6 grams of N,N-dimethylacetamide was added and 1,334 grams of hexamethylcyclotrisiloxane was dissolved therein. To this solution, 844 grams of dimethylvinylchlorosilane was added and the mixture was stirred for 20 hours at room temperature. This mixture was stripped for 3 hours to a head temperature 'of 30C. at 2 mm of mercury and then fractionated on a vigreux column taking 40 ml. cuts. The product was obtained at about 65C. at 0.7 mm of mercury, and had a formula CH CH;

6 In a 3-liter flask, suspended in an ice bath and fitted with a stirring bar, a mixture of 35.85 grams of concentrated ammonium hydroxide, 579 grams of diethylether and 409 grams of ice was stirred until the ice in the flask was melted. To this mixture, while rapidly stirring, 200 grams of CH CH was poured into the flask. The rapid stirring was continued for 5 minutes and the water was separated using a separatory funnel. The ether layer was washed with water until the water was neutral. The ether layer was then stripped under vacuum to a pot temperature of 50C. The product was percent pure as indicated by gas-liquid chromotography and infrared analysis, with a 94.9 percent yield of vinylsiloxane of the formula CH CH CH =CHSi OSi 30H CH CH In a 3-liter flask, 1,838 grams of methyltriacetoxysilane was heated to about 40C. This silane was stirred rapidly while beginning to add 62.4 ml of water slowly from an addition funnel. After the first few milliliters, the temperature was reduced with an ice bath. The total addition time was about 1 hour. Volatile materials were removed under reduced pressure. The resulting partial hydrolyzate had a formula (CH3CO)zSi(OSi) OCCH CH CH OCCHs wherein m had an average of about 0.7.

An adhesion promoter was prepared by slowly adding over a l-hour period 287.5 grams of CH CH I I CH =CHSi(OSi) 0H CH CH to 287.5 grams of the partial hydrolyzate prepared above. The product contained no hydroxyl radicals and was stored in a sealed polyethylene container.

EXAMPLE 2 3 ,91 4, 1 99 7 allowed to stand at least 1 hour before applying a silisive strength of 907.8 p.s.i. with 99.8 percent cohesive cone elastomer to make the adhesion test panels. The failure and in the second test, an average for five panels silicone elastomer was the same in each test and was had an adhesive strength of 772.2 with 63 percent cobasically a diorganopolysiloxane containing methyl and hesive failure. vinyl radicals, an organosilicon compound containing silicon-bonded hydrogen atoms and a platinum cata- EXAMPLE 5 lyst. The test panels were prepared and tested in accor- Adhesion promoters were prepared by mixing in dance with the procedure set forth in ASTM-Designavarying weight ratios, the vinylsiloxane of the formula tion: C273-61 (Reapproved 1970). The silicone elastomer was cured on the panel by heating for 1 hour at 3H3 3H3 150C. The results for this lap shear adhesion test were reported in pounds per square inch and percent cohe- CH2=CHi(Oi) H sive failure. The test results were as shown in Table 1.

CH CH; The panels were tested the same day they were prepared. 15 and the partial hydrolyzate as described in Example 1.

Table I Composition of Reactive Primer Composition Ingredients in weight percent Lap Shear Test Number Weight of Weight percent Adhesive Test Panels percent Reactive Adhesion Ethylpoly- Strength. 7: Cohesive No. Tested Chlorothene Ingredients Promoter silicate Titanate p.s.i. Failure 1 27 none none none none none 176 0 Adhesion promoter prepared same as in Example 1. except (CHQ SiCI substituted for (CH ,=CH)(CH;)=SiCl in the proper molar amount.

EXAMPLE 3 The weight ratios were as shown in Table III. Primer compositions were prepared containing 76.9 weight Test panels were prepared and tested as described in percent Chlorothene and 23.1 weight percent reactive Example 2 using the same materials. After the test paningredients which were the adhesion promoter, ethylels were made, they were aged at room temperature for polysilicate and bis(acetylacetonyl)diisopropyltitanate 1 day before 'the lap shear test was done. The results 40 present in equal weight amounts. Test panels were prewere as shown in Table II. pared and tested as described in Example 1. The lap Table II Composition of Reactive Primer Composition Ingredients in weight percent Lap Shear Test Number Weight of Weight percent Adhesive Test Panels percent Reactive Adhesion Ethylpoly- Strength, Cohesive No. Tested Chlorothene Ingredients Promoter silicate Titanate p.s.i. Failure 1 33 none none none none none 139.3 0 2 31 76.9 23.1 33.3 33.3 33.3 902.7 99.2 3 10 80.0 20.0 40.0 20.0 40.0 835.4 75.5 4 4 81.6 18.4 44.5 33.3 22.2 779 80 5 5 78.4 21.6 36.4 36.4 27.2 683 41 6 5 80.0 20.0 40.0 40.0 20.0 769.2 67.6 7 5 83.3 16.7 50.0 50.0 0.0 965.4 98

EXAMPLE 4 shear test results were as shown in Table III. The results To show the advantages of using an extremely thin are averages for five Panels for each test' layer of primer composition, test panels were prepared Table III as described 111 Example 3, Test No. 2 usmg the same materials and cure conditions, except the prepared test Adheslo" Promoter p Shear Test panels were allowed to stand 2 days after the silicone panial Adhesive elastomer was cured before the lap shear test was done. Test vlPyls'loxanev hydrolyzate, Strength, cqhesive No. welght percent wt. percent p.s.l. Fa1lure In one test, the primed panels were rubbed to remove as much primer composition as possible. In a second 5 22 3 5g :2 test, the primer composition was wiped on and no fur- 3 863 ther effort was used to remove any primer composition. g 22.7 739 23 In the first test, an average for five panels had an adhe- EXAMPLE 6 Test panels were prepared and tested as described in Example 2 using the same materials. After these test panels were made, they were aged at room temperature for 4 days before the lap shear test was done. The results were as shown in Table IV wherein various primer compositions were tested.

Table IV EXAMPLE 8 Composition of Reactive Primer Composition ingredients in weight percent Lap Shear Test Number Weight of Weight percent Adhesive Test Panels percent Reactive Adhesion Ethylpoly- Strength, Cohesive No. Tested Chlorothene ingredients Promoter silicate Titanate p.s.i. Failure "Primer composition stored three months before using in adhesion test.

Table VI Length of Time Time Number Heat Length Temperin allowed of aging of ature contact to dry Adhesive Test Panels Temper- Time of with before Strength, Cohesive No. Tested ature. C. Aged, Water water testing p.s.i. Failure 1 2 150 8 days 728 2 7 150 8 days 1149 100 3 2 250 113 hours 567 100 4 2 250 12 days 335 6 5 2 250 23 days 292.5 0 6 2 Boiling 7 hours 4 days 956 100 7 2 Boiling 24 hours 4 days 762.5 20 8 2 Room 12 days 2 days 823 100 Temp.

Control. no primer used.

EXAMPLE 7 EXAMPLE 9 Test panels were prepared as described in Example 2, Test No. 6 where the room temperature vulcanizable silicone elastomer was allowed to cure at room temperature for a specific period of time before testing. The other conditions of the test were the same and the materials used were the same. The results of the lap shear test were as shown in Table V.

Test panels were prepared and tested as described in Example 2, except in the room temperature vulcanizable silicone elastomer the diorganopolysiloxane contained 3,3,3-trifluoropropylmethylsiloxane units and methylvinylsiloxane units. This silicone elastomer was cured by the same mechanism as described in Example 2, namely, by using a silicon compound containing silicon-bonded hydrogen atoms and a platinum catalyst. The results were as shown in Table VII. The materials used were the same for the primer composition unless indicated otherwise.

Composition of Reactive Ingredients in weight percent Lap Shear Test Primer Composition Number 4 Weight of Weight percent Adhesive Test Panels percent Reactive Adhesion Ethylpoly- Strength. 7: Cohesive No. Tested Chlorothene Ingredients Promoter silicate Titanate p.s.i. Failure 1 25 none none none none none 77.7 O

9 2 82.6 17.4 47.6 47.6 4.8 365 0 l0 5 82.6 l7.4 47.6 47.6 4.8 542 43 ll 1 76.9 23.1 33.3 33.3 33.3 380 100 "The titanate was tetraisopropyltitanate. 'I'est panel aged after preparation for I I4 days before Example 2, except the silicone elastomer was different and was based on a lower viscosity polydiorganosiloxane. The silicone elastomer was allowed to cure at room temperature for various lengths of time before the lap shear test was done.

which was prepared by mixing under anhydrous conditions equal molar amounts of EXAMPLE 10 Test panels were prepared and tested as described in CH CH CH =CHSi (OSi 0H and (CHaCO) z-Si-O-Si (OCCH the lap shear test was done. These times and the test re- CH 3 CH3 sults were as shown in Table VIII. The primer compositions used were as described in Table VIII using the ad- CH CH O hesion promoter indicated and described below. I 3 3 H A. The same adhesion promoter as described in Ex- CH2=CHS1 OS1 303i (OCCHB 3 ample l. I i

CH3 CH3 I I I B. CH =CHSi(OSi OSi(OCCH 2 which was prepared by mixing under anhydrous con- CH CH ditions equal molar amounts of which was prepared by mixing under anhydrous conditions equal molar amounts of CH CH O 40 I 3 3 (3H3 9H3 S). CH =CHSi(OSi) OH and CH3Si(OCCH3 3- CH2=CHSi(0Si) OH and s1(occH3).,

I I I CH3 CH3 CH3 CH 3 9 3 3 9 E. Vinyltriacetoxysilane F. Vinyltrimethoxysilane G. The partial hydrolyzate of methyltriacetoxysilane of Example 1. Test Numbers 2, l3, l4, 15, 21, 22 and 23 were tita- C CH =CHSi (OSi OSi-O-Si (OCCH 2 I I I CH CH OCCH;

0 nium substrates. All other substrates were aluminum.

Table VIII Composition of Primer Composition v in weight percent Lap Shear Test Length Weight Number of cure Weight percent 7 of before percent Reactive Adhesive Test Panels test, Chloro- Ingre- Adhesion Ethylpoly- Strength, Cohesive No. Tested days thene clients 4 Promoter silicate Titanate p.s.i. Failure l" I 7 none none none none none ll 0 2 2 7 none none none none none 23.5 .0 3 4 7 94.3 5.7 33.3A 33.3 33.3 319.5 42.5 4 4 7 76.9 23.l 33.3A' 33.3 33.3 3I9 53.3 5 2 8 76.9,; 23.l 33.3A 33.3 33.3 407.5 6 y 2 34 94.3 .5.7 33.3A 33.3 33.3 448 I 7 2 37 76.9 23.l 33.3A 33.3 33.3 440 82.5 8 2 66 94.3 5.7 33.3A 33.3 33.3 5l5 77.5 9 2 69 76.9 2311 33.3A 33.3 33.3 934 96 I0 6 112 76.9 23.1 33.3A 33.3 33.3 575.8 90.5 I] 2 7 76.9 23.] 333B 33.3 33.3 232.5 6 l2 2 7 83.3 16.7 50 B none 50 4 l3 2 7 76.9 23.1 33.38 33.3 33.3 365 5 Table VIII-continued Primer Composition Composition of in weight percent Lap Shear Test Length Weight Number of cure Weight percent of before percent Reactive Adhesive Test Panels test, Chlorolngre- Adhesion Ethylpoly- Strength. 71 Cohesive No. Tested days thene clients Promoter silicate Titanate p.s.i. Failure 15 2 48 76.9 23.1 33.3B 33.3 33.3 355 16 2 7 76.9 23.1 33.3C 33.3 33.3 452.5 67.5 17 2 18 76.9 23.1 .33.3C 33.3 33.3 475 65 18 2 39 76.9 23.1 33.3C 33.3 33.3 480 50 19 2 7 76.9 23.1 33.3D 33.3 33.3 82.5 0 20 2 7 76.9 23.1 33.3D 33.3 33.3 400 10 21 2" 7 76.9 23.1 33.3D 33.3 33.3 200.5 0 22 2 76.9 23.1 33.3D 33.3"" 33.3 84.0 0 23 2 99.0 1.0 33.3D 33.3 33.3 87.5 0 24 2 7 83.3 16.7 50.0E 0.0 50.0 63 0 25 2 7 83.3 16.7 0.0 50.0 50.0 72.5 0 26 2 7 83.3 16.7 50.0F 0.0 50.0 66 0 27' 2 10 76.9 23.1 33.36 33.3 33.3 42.5 0

"Primer composition painted on the substrate surface with a small brush. "Primer composition sprayed on test panel from an aerosol container.

"Solvent was 64.6 weight percent Chlorothene and 35.4 weight percent trichloromonofluommethane.

Ethylorthosilicate was used in place of the ethylpolysilicate. 'For comparison purposes.

EXAMPLE 1 1 Aluminum test panels were wiped with the primer composition as described in Example 2, a peroxide cured silicone elastomer based on a polydimethylsiloxane gum was then applied to the primed surface and cured for 1 hour at 150C. These test panels were allowed to stand 12 days before the lap shear test was done. Ten test panels had an average adhesive strength of 516 p.s.i. with cohesive failure where the silicone elastomer contacted the primed aluminum panel.

EXAMPLE 12 An adhesion promoter was prepared by mixing equal weight ratios of EXAMPLE 13 The following primer compositions were prepared by mixing the ingredients of each composition in the order shown below. These primer compositions were then used in preparing test panels as described in Example 2. The results of the lap shear test shown below in Table 1X were the averages of five test panels for each set of values shown.

A. Primer composition 96.2 weight percent Chlorothene and 3.8 weight percent reactive ingredients Reactive lngredients 41.7 weight percent partial hydrolyzate of methyltriacetoxysilane as defined in Example 1, 41.7 weight percent of the vinylsiloxane defined in Example 1, 8.3 weight percent of ethylpolysilicate, and V 8.3 weight percent of bis(acetylacetonyl)diisopropyltitanate. B. Primer Composition 83.3 weight percent Chlorothene 16.7 weight percent reactive ingredients Reactive ingredients 25.0 weight percent vinylsiloxane as defined in Example 1, 25.0 weight percent of the partial hydrolyzate of methyltriacetoxysilane defined in Example 1, and 50.0 weight percent ethylpolysilicate C. Primer Composition 83.3 weight percent Chlorothene l6.7 weight percent reactive ingredients Reactive lngredients 25.0 weight percent vinylsiloxane as defined in Example 1, 25.0 weight percent of the partial hydrolyzate of methyltriacetoxysilane defined in Example 1, and 50.0 weight percent bis(acetylacetonyl)diisopropyltitanate. D. Primer Composition 91.0 weight percent Chlorothene 9.0 weight percent reactive ingredients Reactive lngredients 50.0 weight percent vinylsiloxane as defined in Example 1, 50.0 weight percent of the partial hydrolyzate of methyltriacetoxysilane defined in Example 1. E. Primer Composition 76.9 weight percent Chlorothene 23.] weight percent reactive ingredients Reactive lngredients 33.3 weight percent ethylpolysilicate 16.7 weight percent of the partial hydrolyzate of methyltriacetoxysilane as described in Example 1,

33.3 weight percent bis(acetylacetonyl)diisopropyltitanate, and

16.7 weight percent of the vinylsiloxane defined in Example 1. F. Primer Composition 76.9 weight percent Chlorothene 23.1 weight percent reactive ingredients Reactive Ingredients 16.7 weight percent of the vinylsiloxane defined in Example 1, 16.7 weight percent of the partial hydrolyzate of methyltriacetoxysilane as described in Example 1, 33.3 weight percent ethylpolysilicate and 33.3 weight percent bis(acetylacetony1)diisopropyltitanate. G. Primer Composition 76.9 weight percent Chlorothene 23.1 weight percent reactive ingredients Reactive Ingredients 16.7 weight percent of the partial hydrolyzate of methyltriacetoxysilane as described in Example 1, 16.7 weight percent of the vinylsiloxane as described in Example 1, 33.3 weight percent ethylpolysilicate, and 33.3 weight percent bis(acetylacetonyl)diisopropyltitanate. H. Primer Composition 76.9 weight percent Chlorothene 23.1 weight percent reactive ingredients Reactive Ingredients 33.3 weight percent ethylpolysilicate, 16.7 weight percent of the vinylsiloxane as described in Example 1, 33.3 weight percent bis(acetylacetonyl)diisopropylmixing 76.9 weight percent Chlorothene and 23.1 weight percent reactive ingredients wherein the reactive ingredients were equal weight amounts of the above adhesion promoter, ethylpolysilicate and bis- (acetylacetonyl)diisopropyltitanate. Aluminum test panels were prepared and tested as described in Example 2. The adhesive strength was 984 p.s.i. with 100 percent cohesive failure for an average of five panels.

B. A primer composition was prepared by mixing 76.9 weight percent Chlorothene and 23.1 weight percent reactive ingredients wherein the reactive ingredients were 16.7 weight percent dimethylvinylsilanol, 33.3 weight percent ethylpolysilicate, 33.3 weight percent bis(acetylacetonyl)-diisopropyltitanate and 16.7 weight percent methyltriacetoxysilane. Aluminum test panels were prepared and tested as described in Example 2. The adhesive strength was 927 p.s.i. with 100 percent cohesive failure for an average of five test panels.

EXAMPLE 15 Primer compositions were prepared and tested as described in Example 2, except normal-propylorthosilicate was used in place of ethylpolysilicate. The results on aluminum test panels were 765 p.s.i. with 71.5 percent cohesive failure for an average of two test panels.

EXAMPLE l6 Primer compositions were prepared and tested as described in Example 2, except the concentrations of ingredients were varied as described in Table X wherein the results were as shown for the lap shear test.

Table X Primer Composition Composition of Reactive ingredients in weight percent Lap Shear Test Number Weight of Weight percent Adhesive Test Panels percent Reactive Adhesion Ethylpoly- Strength, Cohesive No. Tested Chlorothene Ingredients Promoter silicate Titanate p.s.i. Failure That which is claimed is: 1. A composition under anhydrous conditions consisting essentially of an organic solvent solution of titanate, and 16.7 weight percent of the partial hydrolyzate of methyltriacetoxysilane as described in Example 1.

Table IX a. a reaction product obtained by mixing under essentially anhydrous conditions Shear Test 1. an organosiloxane of the formula CSlVe Primer Strength, Cohesive Composition p.s.i. Failure A 853 99.8 CH CH B 887 100 I g fig ASi(OSi) OH E 843 100 F 866 100 CH CH G 876 100 H 852 100 EXAMPLE 14 in which A is a monovalent radical selected from the group consisting of vinyl and methyl radicals and k has an average value of from 0 to 20 inclusive where the organosiloxane species having values of k above 20, is present, are in no more than minor amounts and 2. an acetoxysilicon compound of the formula A. An adhesion promoter was prepared by mixing under anhydrous conditions 24.7 parts by weight of dimethylvinylsilanol and 75.3 parts by weight of the partial hydrolyzate of methyltriacetoxysilane as defined in Example 1. A primer composition was prepared by 3) z-y 3 )2"'y O I! I I II (CH CO) l ysi Oi OCCH OCCH sl m in which m has an average value of from 0 to inclusive and y is l or 2,

(l) and (2) being mixed in proportions to provide a ratio of hydroxyl in (l) to acetoxy in (2) of from l/l4 to b. an alkyl silicate selected from the group consisting of ethylorthosilicate, propylorthosilicate, ethylpolysilicate and propylpolysilicate, and

c. an organotitanate of the formula wherein each OR is a monovalent radical selected from the group consisting of alkoxy radicals having from 1 to 5 carbon atoms and acetylacetonoxy, (a) provides 5 to 100 weight percent, (b) provides 0 to 50 weight percent and (c) provides 0 to 50 weight percent, where (a), (b) and (c) equals 100 weight percent, said organic solvent solution being from 50 to 99.9 weight percent of an organic solvent selected from the group consisting of ketones, halogenated hydrocarbons and hydrocarbons all having boiling points no greater than 150C.

2. The composition in accordance with claim 1 in which A is the vinyl radical.

3. The composition in accordance with claim 2 in which the organic solvent solution is from 75 to 99 weight percent organic solvent and (b) is present in at least weight percent and (c) is present in at least 4 weight percent.

4. The composition in accordance with claim 3 in which the organic solvent is inhibited l,1,l-trichloroethane.

5. The composition in accordance with claim 2 in which k is 3 and (l) and (2) are mixed in proportions which provide 50 weight percent (1) and 50 weight percent (2).

6. The composition in accordance with claim 5 in which the organic solvent is from 75 to 99 weight percent chlorothene and (b) is present in an amount of at least 10 weight percent and (c) is present in an amount of at least 4 weight percent.

7. The composition in accordance with claim 4 in which k is 3, (l) and (2) are mixed in proportions which provide equal molar amounts of l) and (2) and the acetoxysilicon compound is methyltriacetoxysilane.

8. The composition in accordance with claim 4 in which k is 3, (1) and (2) are mixed in proportions which provide equal molar amounts of 1) and (2) and the acetoxysilicon compound has a formula (011300) 2si-o-sit 0001ia 2 CH CH 18 percent, (b) is present in an amount of at least 20 weight percent and (c) is present in an amount of at least 10 weight percent.

11. The composition in accordance with claim 4 in which k is 3, (l) and (2) are mixed in proportions which provide equal molar amounts of l and (2) and the acetoxysilicon compound is tetraacetoxysilane.

12. The composition in accordance with claim 1 in which the ratio of hydroxyl in (l) to acetoxy in (2) is from /8 to 13. The composition in accordance with claim 7 in which the organotitanate is bis(acetylacetonyl)diisopropyltitanate.

14. The composition in accordance with claim 8 in which the organotitanate is bis(acetylacetonyl)diisopropyltitanate.

15. The composition in accordance with claim 9 in which the organotitanate is bis(acetylacetonyl)diisopropyltitanate.

16. The composition in accordance with claim 10 in which the organotitanate is bis(acetylacetonyl)diisopropyltitanate.

17. The composition in accordance with claim 11 in which the organotitanate is bis(acetylacetonyl)diisopropyltitanate.

18. A composition under anhydrous conditions consisting essentially of an organic solvent solution prepared by mixing I. an organosiloxane of the formula CH CH ASi (0S1) OH CH CH in which A is a monovalent radical selected from the group consisting of vinyl and methyl radicals and k has an average value of from O to 20 inclusive where the organosiloxane species having values of k above 20, if present, are in no more than minor amounts,

2. an acetoxysilicon compound of the formula 0 a)2-y (CH3)2y O n I I II (CH CO) 1 3 51 0-?1 OCCH in which m has an average value of from O to 5 inclusive and y is l or 2,

b. an alkyl silicate selected from the group consisting of ethylorthosilicate, propylorthosilicate, ethylpolysilicate and propylpolysilicate, and

c. an organotitanate of the formula Ti(OR),,

19 20 organic solvent solution being from 50 to 99.9 weight 150C, percent of an organic solvent ele e fr m h gr p 19. The composition in accordance with claim 18 in consisting of ketones, halogenated hydrocarbons and hi h A i th vin l r dical,

hydrocarbons all having boiling points no greater than 5 

1. A COMPOSITION UNDER ANHYDROUS CONDITIONS CONSITING ESSENTIALLU OF AN ORGANIC SOLVENT SOLUTION OF A. A REACTION PRODUCT OBTAINED BY MIXING UNDER ESSENTIALLY ANHYDROUS CONDITION
 1. AN ORGANOSILOXANE OF THE FORMULA
 2. AN ACETOXYSILICON COMPOUND OF THE FORMULA
 2. an acetoxysilicon compound of the formula
 2. The composition in accordance with claim 1 in which A is the vinyl radical.
 2. an acetoxysilicon compound of the formula
 3. The composition in accordance with claim 2 in which the organic solvent solution is from 75 to 99 weight percent organic solvent and (b) is present in at least 10 weight percent and (c) is present in at least 4 weight percent.
 4. The composition in accordance with claim 3 in which the organic solvent is inhibited 1,1,1-trichloroethane.
 5. The composition in accordance with claim 2 in which k is 3 and (1) and (2) are mixed in proportions which provide 50 weight percent (1) and 50 weight percent (2).
 6. The composition in accordance with claim 5 in which the organic solvent is from 75 to 99 weight percent chlorothene and (b) is present in an amount of at least 10 weight percent and (c) is present in an amount of at least 4 weight percent.
 7. The composition in accordance with claim 4 in which k is 3, (1) and (2) are mixed in proportions which provide equal molar amounts of (1) and (2) and the acetoxysilicon compound is methyltriacetoxysilane.
 8. The composition in accordance with claim 4 in which k is 3, (1) and (2) are mixed in proportions which provide equal molar amounts of (1) and (2) and the acetoxysilicon compound has a formula
 9. The composition in accordance with claim 6 in which m has an average value of 0.5 to 1 inclusive and y is
 1. 10. The composition in accordance with claim 9 in which (a) is present in an amount of at least 10 weight percent, (b) is present in an amount of at least 20 weight percent and (c) is present in an amount of at least 10 weight percent.
 11. The composition in accordance with claim 4 in which k is 3, (1) and (2) are mixed in proportions which provide equal molar amounts of (1) and (2) and the acetoxysilicon compound is tetraacetoxysilane.
 12. The composition in accordance with claim 1 in which the ratio of hydroxyl in (1) to acetoxy in (2) is from 1/8 to 1/2 .
 13. The composition in accordance with claim 7 in which the organotitanate is bis(acetylacetonyl)diisopropyltitanate.
 14. The composition in accordance with claim 8 in which the organotitanate is bis(acetylacetonyl)diisopropyltitanate.
 15. The composition in accordance with claim 9 in which the organotitanate is bis(acetylacetonyl)diisopropyltitanate.
 16. The composition in accordance with claim 10 in which the organotitanate is bis(acetylacetonyl)diisopropyltitanate.
 17. The composition in accordance with claim 11 in which the organotitanate is bis(acetylacetonyl)diisopropyltitanate.
 18. A composition under anhydrous conditions consisting essentially of an organic solvent solution prepared by mixing
 19. The composition in accordance with claim 18 in which A is the vinyl radical. 